A Skyworth cool open 42K1Y LCD appears red indicator light does not turn on, check the power board output 12V normal, motherboard 12V to 5V, 3.3V, 1.2V normal, but 3.3V to 1.2V, 2.5V (U1P6, U1P8) two groups There is no voltage measurement input and no voltage. Check the data. The two groups of power supply are controlled by the standby switch tube Q8. The measurement Q8 has damaged the open circuit. The tube is the patch FET AO3401A, and the tube that can be replaced can not be found at the moment. Just found that an old display high-voltage board has a patch FDS9435A, the parameter power is definitely better than the original tube, and the lead connection is used to successfully eliminate the fault. Here is the repair picture time relationship picture order is a bit messy Water Proof For Switch And Socket IP55 water proof, switch socket water proof , high pressure water proof Guangdong Shunde Langzhi Trading CO., Ltd , https://www.langzhielectrical.com